Method for continuous nondisturbing monitoring of blood pressure by magnetoelastic skin curvature sensor and ECG

Abstract

This paper concerns continuous nondisturbing estimation of blood pressure using mechanical plethysmography in connection with standard electrocardiography (ECG). The plethysmography is given by a novel magnetoelastic skin curvature sensor (SC-sensor) applied on the neck over the carotid artery. The sensor consists of a magnetoelastic bilayer partly enclosed by a coil. Bending the bilayer causes large changes of magnetic permeability which can be measured by the coil. The SC-sensor signal and the ECG signal are adaptively processed in order to estimate blood pressure according to a specifically established theoretical model. The model uses estimated vessel radius changes and pulse transit time as parameters. The results show cross correlation coefficients in the range 0.8 up to 0.9 between reference and estimated values of systolic blood pressure, diastolic blood pressure, and systolic/diastolic blood pressure change, whereas the estimation error was below 4 + 7 mmHg at rest and increased with the stress level. Limitations of the model applicability are given by a hysteretic behavior of both model parameters due to inert changes in artery stiffness. The SC-sensor and the ECG electrodes cause minimal inconvenience to the patient and offer an approach for a continuous nondisturbing monitoring of blood pressure changes, as being relevant for sleep monitoring or biomechanic feedback.Index Terms-Blood pressure, electrocardiography, magnetoelastic amorphous ribbons, mechanical plethysmography, physiological sensors, skin curvature sensor.

Continuous and Noninvasive Measurement of Systolic and Diastolic Blood Pressure by One Mathematical Model with the Same Model Parameters and Two Separate Pulse Wave Velocities

“…However, in many available results, a single PTT and a model with different model parameters are used to estimate SBP and DBP. 16,22,28 In this way, the model parameters are changing at a fast rate when BP changes significantly and rapidly. Consequently, intermittent recalibration using external device is inevitable.…”

Continuous and Noninvasive Blood Pressure Measurement: A Novel Modeling Methodology of the Relationship Between Blood Pressure and Pulse Wave Velocity

“…The model coefficients are identified by individual calibration. 1,3,4,6,7,[9][10][11][12]15 Theoretical modeling of the relationship between BP and PTT/PWV is a crucial part in the methodology above. So far, the proposed theoretical models fall into two categories: linear models and nonlinear models.…”

“…3 Some researchers considered the nonlinearity of the elastic property of the vascular wall and established two typical non-linear models. 4,6,[9][10][11] …”

“…1,3,4,6,7,[9][10][11][12]15 But PAT includes pre-ejection period that may introduce large errors to real PTT. To avoid this problem, two pulse waves are acquired using infrared light PPG sensors located at ear and toe in our study.…”

Fabrication and characterization of magnetic composite membrane pressure sensor

“…The polymer PDMS enables the creation of a membrane with extremely low stiffness coefficient, which exhibits large deflection when subject to pressure. The amorphous magnetic alloy Vitrovac® has been utilized for various sensing applications before [9][10][11][12] owing to its soft magnetic properties. It possesses extremely high magnetic permeability [13] and increases the variation of magnetic flux density in the vicinity of the planar coils, due to the deflection of the membrane.…”